What to know about wasps, as their presence persists with the warm weather

A yellowjacket wasp. (Pexels)

Anyone who’s attempted to eat outside while the temperatures are warm enough to do so will likely notice a pesky presence.

Wasps are still out in full force, circling barbeques and picnics, farmers markets and outdoor food stands. Critters like yellowjackets and hornets thrive in Canada during the warmer months, when they can often be seen and heard anywhere food or drink is present. Their persistence is hard to ignore, and neither are their numbers. But are there more of these bothersome bugs than in past years?

Do we know if there are more wasps this year?

Darryl Gwynne is an emeritus professor of biology with the University of Toronto. He says several censuses would be needed to assess the numbers of wasps over the years, which would be a challenging task. There also isn’t any such data currently available. However, he believes that their numbers are the same as previous years.

“I suspect it’s simply the time of year for their activity, and they’re out there doing their thing,” he told CTV News.

Wasps are at their peak around July, when their nests are at their maximum and growing. The ones that don’t reproduce, known as workers, are the ones that are out and about, bugging us when we’re eating outside. Gwynne said they’re looking for food and sugar to help fuel their energy.

“That’s why it’s really important to keep any sugary drink well covered because the wasp will sometimes go inside,” he said.

During the summer months, queens are generally in their nests. However, if you see wasps or hornets in early spring, those are the queens, as the workers haven’t hatched yet.

When do wasps and hornets die?

The insects are ectothermic, which means their internal temperature largely relies on the external temperature. Gwynne describes the insect as an annual species, with most of the broods dying upon first frost. The queens, however, will mate and then hibernate throughout the winter.

“They store the sperm in special sperm-storing pouches and burrow down into leaf litter or log piles,” he explains. “They overwinter and start their nests the following spring, usually by themselves.”

If warmer weather persists into the fall, Gwynne says to expect to keep seeing them around for longer. Research he conducted in New Zealand found that yellowjackets will continue growing their nests so long as the weather permits.

“We really are lucky that we get severe frosts here in October or November, which nails these things dead,” he said. “We know that if Canada didn’t have their first early frost until February, we’d probably have nests still growing,” he says.

What do nests look like?

Wasp and hornet nests vary in texture, shape and location.

A paper wasp’s nest resembles an upside-down umbrella with a honeycomb pattern, supported by a single stalk. They build nests in various locations, from tree branches to parts of buildings like eaves and windowsills.

Bald-faced hornets’ nests, which look like paper mâché balls, are built above ground and can grow to be the size of a football.

Mud daubers’ nests are tubular in shape, made of dirt rather than wood fibres and are usually found in dry places like attics, eaves, and decks.

Yellowjacket nests have a single hole opening and can be found above or underground in hollowed trees, decks, eaves and even woodpiles.

How to deal with wasps and hornets?

If there’s a wasp problem in or around your property, experts stress it’s best to get a professional in to deal with the problem. Since they love to feed, it’s best to remove any leftover vegetation from gardens on the property. Also, don’t leave out any meats or sugary drinks, as the insects are most drawn to those smells.

Dr. Andrew Young, an assistant professor at the University of Guelph’s school of environmental sciences, told CTV News last year that it’s best not to disturb the nest.

“If there’s a wasp nest in a tree or something, it’s only going to be there for the one year. They don’t survive multiple years. I just give them their space.”